The present invention relates generally to motion picture projectors and more particularly to a control arrangement to selectively cease film transporting upon the occurrence of a predetermined film tension condition.
Motion picture projectors normally include a forward and reverse film transporting drive assembly and a controller assembly which is manually moveable into various positions for selecting corresponding operating modes. A motion picture projector of this type is described in U.S. Pat. No. 3,952,969 which issued to J. G. Woodier on Apr. 27, 1976.
During normal projection modes, forward and reverse for example, it is desirable to automatically cease the film transporting action when a high film tension condition is sensed. Such a film tension condition may occur when the end of the film is reached during normal forward projection or at various other times whenever the suitable for their intended purpose, these arrangements are either overly complex, unreliable or are not easily adaptable to the film drive and control mechanisms of projectors currently available. Further, many of the prior arrangements are not disabled during certain operational modes such as still, pause, fast forward and rewind where either high film tension normally occurs or the operator may inadvertently actuate the arrangement.
In accordance with the present invention, it is a principal object to provide an improved arrangement in a projector to automatically cease film transporting when a predetermined film tension condition occurs in predetermined operating modes.
It is a further object of the present invention to provide a simplified and reliable arrangement to automatically cease film transporting in a projector upon the occurrence of a predetermined film tension condition which is conditioned to a sensing mode by the mode controller assembly of the projector and which ceases film transporting action by positioning of the mode controller assembly.
It is another object of the present invention to provide an arrangement to cease film transporting of a projector upon the occurrence of a predetermined film tension condition that includes a locking arrangement to inhibit operation in certain predetermined operational modes.
It is yet another object of the present invention to provide an automatic stopping arrangement in a projector when a high tension film condition is detected that is easily adaptable to projector apparatus and avoids one or more of the above-described disadvantages of the prior art arrangements.
These and other objects of the present invention are efficiently achieved by providing a control arrangement to selectively cease film transporting of a projector upon the occurrence of a predetermined film tension condition. A manually moveable mode controller assembly of the projector is effective to position the film transport ceasing control arrangement into a reset enabled condition. A selectively responsive transmitting assembly is provided to transmit the occurrence of the predetermined film tension condition from a film tension sensing arrangement to a reset condition establishing member when the mode controller assembly is positioned in predetermined modes such as normal forward and reverse modes. In other modes such as fast forward, pause, still and rewind, the selectively responsive transmitting assembly is provided with a release locking assembly to inhibit the transmission of the occurrence of the predetermined film tension condition to the reset member of the reset condition establishing member.
The selectively responsive transmitting assembly includes a pivotal release arm that controls the position of the reset member and is pivoted to release the reset member when the predetermined film tension condition occurs in the selected responsive modes. The reset member is an elongated arm provided with a positioning extension and biased vertically to position the mode controller assembly to cease film transporting action when the reset arm is released by the transmitting assembly. The film tension sensing arrangement includes a pivoted spring wire carrying a roller over which the film is placed in the film path of the projector with increasing film tension displacing the spring wire to a predetermined position. The release arm is provided with a cradle arm which is positioned to be responsive to movement of the spring wire. The release locking arrangement in one arrangement includes a moveable locking member which is either linearly displaced or pivoted to a position in selected modes to prevent pivoting of the release arm due to movement of the spring wire of the tension sensing arrangement.